The purpose of the study is to investigate a new drug for rheumatoid arthritis called Trocade. Trocade has been designed to help prevent the bone and joint changes that occur in this disease. It does this by inhibiting a specific molecule in the mechanism by which arthritis destroys the joints. This study is being conducted to see if Trocade works and whether it is safe. Unlike other treatments, Trocade may not immediately improve the symptoms of arthritis. Therefore, it will be given in addition to treatments which help these symptoms. The methotrexate you have been taking is one of these drugs. This study will determine if adding Trocade to methotrexate prevents joint damage, compared to if methotrexate was taken alone.